||This involves interviewing end-users, managers and other business people to identify their requirements. These are usually different depending on each person's business focus, so an important part of this exercise is ensuring that no business requirements are overlooked. These requirements must be documented in such a way that any employee of the business can understand them without having to possess any particular technical expertise. It is critical that the business people themselves confirm that the requirements as documented are accurate and comprehensive.|
||Most complex information technology systems are designed using a "multi-tier" approach. There are typically at least three "tiers" or layers, one each for the database (the back-end), the business logic (the middle layer) and the user interface (the front-end). Sometimes these tiers are themselves separated into sub-tiers. The important philosophy behind this approach is that each tier is separate and independent, and only communicates with the tier "above" it and "below" it. Both the front-end and the back-end only communicate with the business logic ; the business logic is there to link the front-end and back-end together, which explains why it is sometimes called the "middle layer".|
||When you have completed a comprehensive business analysis followed by a design of the components that will be needed to implement these business requirements, you then need to write the programs that will actually do the work. You would think that if the previous two steps had been done thoroughly and completely that building the solution would be simple ; unfortunately this is rarely the case. There is no doubt that analysing and designing properly helps significantly during the application construction phase, but it is not by any means a guarantee of success. However, NOT doing the analysis and design properly is almost certainly a guarantee of failure.|
||Installing a newly-completed application and configuring it for first-time use in the real world often presents its own set of challenges.|
||There are several kinds of documentation, including technical, user, business and marketing.
- Technical documentation describes how a system was designed and written and is often useful to other developers who have to work on the system. By definition, such documentation must be written by the original developers themselves.
- User documentation describes the functioning of a system and is used by the people who will eventually operate it. Such documentation is best written by users, not developers.
- Business documentation includes post-implementation reviews, case studies and white papers.
- Marketing documentation is often made available to the public or the media via press releases or on a company's web site.
||On occasion both users and developers need to be trained if their skills are lacking.|
||Fully two-thirds of the overall cost of an information technology system is taken up by ongoing maintenance. It is a mistake to think that once a system is implemented and stable that no further changes will be needed - business requirements change extremely rapidly in the modern world and computer systems have to evolve to meet that change.|